Tuning a Ameritron AL811H with the FT897D
I seem to be only seeing 600W on SSB. Radio RF power is set at 80W. I'm a newbie with this amp. Any tuning assistance would be much appreciated!
Radio: Yaesu FT-897D
Amp: Amreitron AL-811H
Seeing 600W using what to indicate the power?
A PalStar PM2000A. Also, the load & tune dials have a red indicator as well as a white notch in the dial itself. What's the red pointer for? The manual doesn't mention them.
The PM2000A's not bad (also not great...I have one in the shop, and it can be off more than 10%). I assume you're using the PEAK mode?
The red pointer points at the numeric markings on the PLATE and LOAD controls so once you find the correct settings, you can re-set the controls by referring back to those settings and not having to "tune up" all over again, each time. The white notch means nothing.
I have an FT-857D and an AL572
Originally Posted by W7TRD
While there are a lot of factors that affect the power output, there are two things right off the top:
1 - What is the line voltage you are powering the amp with? 600W peak isn't really that far off for 80W drive. If the line voltage is sagging, you won't see the advertised output power. You can run a new AC circuit, or put the amp on its own circuit. If the lights dim, or you measure the line voltage and see it sag when you transmit - that is probably why you aren't seeing the rated output.
2 - The WARC bands are usually a compromise and the input tuning favors the "regular" bands. The SWR on the input can be somewhat high, which causes your rig to fold back the power on the input. You might actually be driving it with less power than you think.
What bands? What is the SWR on the input to the amp between your 897D and the amplifier?
600W on SSB with an 811H really isn't far off the mark. What happens if you increase and decrease the drive? (assuming the radio isn't folding back power)
They are Vernier dials. Read the red pointer. The other is just a mark on the knob.
I agree with Charley's comments.
There's also lots to know about tuning any amplifier, not just that one (they really all tune the same way), including making sure your LOAD control is set as far clockwise as possible to maximize output power while minimizing grid current.
The 811H should run at well under 200mA grid current when it's properly loaded. If the Ig is higher than that, good chance it's not loaded properly or isn't looking into a very good match.
Here she is. An Ameritron AL-811H with 4 brand new 811A tubes. Runs nice & quiet. After a bit of tuning and getting use to the amps characteristics, with 80W drive, I'm seeing 650-700W SSB on the PalStar PM2000 meter. Watts seem to be very clean. Great reports, and I'm not bleeding over on any of our household electronics.
Thanks for the inputs!
So, what did you do to boost this from 600W (first post) to 700W (now)?
Originally Posted by W7TRD
Adjusted radio, amp, and meter for optimum results.. I guess a Bird meter is next on the list...
80 watt drive is too high for an 811H. If you are tuning and loading properly with a CW carrier, you will have full output from that amp at 60 to 65 watts of drive. Then switch your rig to SSB and you'll be getting full output without splattering.